At least 60 protesters showed up on the doorstep of the Barack Obama campaign headquarters in Oakland Thursday night, where they demanded the freedom of Bradley Manning, the Army private accused of leaking government secrets to WikiLeaks.

Manning, 24, has been indicted on 22 counts including charges of aiding the enemy.

Video posted to YouTube showed protesters lingering at the entrance to the office, while a member of the advocacy group Iraq Veterans Against the War presented a letter to campaign volunteers about Manning, demanding they fax it to the White House.

Within minutes, a scuffle broke out between the volunteers and protesters, though it was unclear how it started.

A protester who filmed the scuffle, two-time Iraq war veteran Scott Olsen, says he saw pushing, shoving, and even chairs being wielded, some of which can be seen on the video. Olsen was one of the most well-known faces of the Occupy movement last year after he was seriously injured by what was believed to have been a police projectile during a protest in Oakland.

According to the Oakland Tribune, seven protesters eventually successfully planted themselves inside the campaign office, where they linked arms and told police they would not leave.

After several hours of negotiations with officers, one of the protesters left the office and the remaining six were arrested for trespassing.

According to Rainey Reitman, director of activism at the digital rights advocacy group the Electronic Frontier Foundation and a speaker at the free Manning rally that preceded the protest, the letter was successfully faxed to the White House before the protest ended.

"President Obama made a... statement in May 2011: 'In the 21st century, information is power,' " the letter read.

"We now ask that President Obama honor those words by freeing American truth-teller Bradley Manning."

Earlier this month, according to local media reports, the same campaign office had a window smashed when a group of protesters marched through Oakland's downtown.

Elizabeth Flock is a staff writer for U.S. News & World Report. You can contact her at eflock@usnews.com or follow her on Twitter and Facebook.